Jocelyne Bachevalier - US grants

Early damage to the limbic system (amygdalohippocampal complex) in primates results in a severe and global loss of cognitive memory, though specific learning skill abilities are spared. This profound cognitive deficit is accompanied by emotional and social abnormalities resembling strikingly to those seen in autistic children. In short, these previous findings suggest that damage to the limbic system might have severe consequences on the development of cognitive and socioemotional behavior in primates. The present proposal is aimed at following these earlier findings in defining whether damage to the entire limbic system is necessary to produce the full-fledged syndrome or whether the syndrome can result from damage to specific parts of this complex. For this purpose, a group of investigators with special expertise in primate behavior, neuroendocrinology, neuroanatomy, and neurochemistry is assembled in the proposal to investigate the long-term consequences of neonatal damage to either the amygdaloid complex or the hippocampal formation on the development of (1) cognitive functions, (2) emotional behavior. (3) neuroendocrinological functions. and (4) brain morphological and neurochemical reorganization. The animals are already available and their cognitive and socioemotional behavior has been assessed by the P.I. when they were infants and juveniles. The present proposal is to determine the long-term consequences of these early selective limbic lesions by retesting the same animals as they have reached adulthood. The behavioral investigation will include a battery of behavioral tasks to assess a wide range of cognitive functions, emotional reactions, and food preference that will define specifically the functions that are lost vs those that are spared. The neuroendocrinological functions will be evaluated by modem endocrinological techniques and the reorganization of the brain will be studied by specific morphological and cytoimmunochemistry procedures. This research will provide the first comprehensive evaluation of the behavioral development of monkeys with neonatal restricted lesions of the limbic system and will permit direct correlations between behavioral changes with modifications of neuroendocrinological functions and specific reorganization of brain morphology and transmitter-specific systems. In addition, It will provide (1) experimental models of extreme value to elucidate the pathological bases of several developmental disorders such as autism, schizophrenia, and learning disabilities and (2) a point of departure for many future research aimed at the search for the causes of the limbic system neuropathology in developmental disorders as well as a search for possible treatment. Finally, the behavioral tasks used in the present proposal to assess cognitive functions in primates with specific limbic lesions can be directly standardized to develop non-invasive markers for assessing limbic system insult and integrity during the first years of life in human infants.

DESCRIPTION (Adapted from applicant's abstract): Recent research in the neurobiology of primate memory has called into question the role of the hippocampal formation in memory processing. Instead the (ento- and peri-) rhinal cortical areas seem to be the neural areas crucial for memory. Because monkeys are typically tested in single-item recognition memory tasks which human amnesiacs with hippocampal damage can solve, a monkey task similar to the amnesic patients' memory tasks needed to be developed. We have developed such a task; it is a list memory task in which monkeys can perform well. This task provides serial position primacy and recency effects (good memory for the first and last items, respectively) which reflect separate underlying memory processes. Three groups of 6 monkeys each will receive either bilateral excitotoxic lesions of the hippocampal formation, bilateral aspiration lesions of the rhinal cortex, or none (controls). They will be tested pre- and post-surgically in the list memory task in which retention interval and interference will be parametrically manipulated over a substantial range. These manipulations have been shown to produce significant and definable changes in primacy and recency effects of the serial position function. Performance of the operated monkeys will be compared to that of control animals and their own pre-surgical performance in the list-memory task. This project is designed to further our understanding of the neural basis of memory processing and may provide insights into the neural substrates underlying human cognitive processes and deficits associated with aging and disease states, such as Alzheimer's and Parkinson's.

DESCRIPTION (Adapted from applicant's abstract): Early damage to large portions of the medial temporal lobe has far more severe consequences on the development of cognitive and socioemotional behavior in primates than late damage. The new program of studies described in the proposal is aimed at following these earlier findings in defining which structures in the medial temporal lobe are crucial for the development of normal memory abilities and the formation and establishment of social bonds. We will begin with a study of the effects of early vs. late damage to the hippocampal formation. Earlier studies have often suffered either from the lack of discrete lesions, comprehensive histological analysis or appropriate and sophisticated behavioral assessment, such that the lesion effects reported are inconclusive. The program of studies outlined in this application uses sophisticated MRI-guided excitotoxic hippocampal lesions newly designed memory tasks, extensive characterization of behavioral changes and state of the art anatomical techniques to investigate a) the development of hippocampal functions in monkeys, b) the long-term consequences of early vs. late hippocampal insult on the maturation of memory processes and social bonds, c) the anatomical organization of the efferent projections systems from entorhinal, perirhinal, and parahippocampal areas and, d) the anatomical reorganization of these efferent systems as a result of early hippocampal lesions as compared to adult lesions. Considering that dysfunction of the hippocampal formation contributes to behavioral changes accompanying several devastating neurological disorders, including Dementia, Alzheimer's disease, Schizophrenia and Autism, this unique program of research in monkeys will ultimately lead to the discovery of ways in which such disorders can be alleviated or even eliminated.

One finding emerging from our research program is that insult to the medial temporal lobe in monkeys, and more specifically the amygdala, results in an array of behavioral changes that mimic in many ways the behavioral disturbances seen in autistic people. The goal of the present project is to pursue our investigation of this putative animal model of autism by testing the effects of early versus late lesions of a neural network that includes the amygdala and orbitofrontal cortex. For this purpose, using newly developed neurosurgical procedures and behavioral tasks, we will first evaluate the effects of selective bilateral lesions of the orbitofrontal cortex and amygdala in adult monkeys on cognitive tasks, fearful responses, and social bonds. Second, we will follow the long-term effects of early selective bilateral lesions of the orbitofrontal cortex and amygdala on cognitive tasks, fearful responses, and social bonds in the developing monkeys. These studies will provide the unique opportunity to examine in the same animals cognitive functions, regulations of emotions, and formation and maintenance of social bonds. Also, these studies will allow direct comparison between early versus late lesions that may indicate whether the early lesions he a beneficiary or a more debilitating behavioral effects. Impairment in monkeys with these early and late lesions will be compared to that of participants with autism (Project I). Finally, the monkeys will participate in Project II Aim 2 and Project IV to establish the impact of these lesions on brain systems distant from the neural insult, such as prefrontal cortex and cingulate. Through, such research, principles of the brain's response to damage will ultimately advance our understanding of the basic development processes that follow early dysfunction of the orbitofrontal-limbic circuit in primates, its implication for developmental disorders, such as autism, and leads eventually to discovery of ways by which such effects can be alleviated or even eliminated.

0-11 years old; 21+ years old; Adult; Autism; Autism, Early Infantile; Autism, Infantile; Autistic Disorder; Behavioral; Brain; CRISP; Child; Child Youth; Children (0-21); Collection; Computer Retrieval of Information on Scientific Projects Database; Data; Development; Diagnosis; Encephalon; Encephalons; Eye; Eyeball; Funding; Goals; Grant; Human; Human, Adult; Human, Child; Human, General; Individual; Institution; Investigators; Kanner's Syndrome; Lesion; Man (Taxonomy); Man, Modern; Measures; Methods and Techniques; Methods, Other; Monkeys; NIH; National Institutes of Health; National Institutes of Health (U.S.); Nervous; Nervous System, Brain; Participant; Performance; Process; Research; Research Personnel; Research Resources; Researchers; Resources; Science of neurophysiology; Source; Techniques; United States National Institutes of Health; adult human (21+); children; developmental disease/disorder; developmental disorder; neural; neural mechanism; neuromechanism; neurophysiology; relating to nervous system; social communication; youngster

CRISP; Computer Retrieval of Information on Scientific Projects Database; Cues; Emotional; Equipment; Eye; Eyeball; Funding; Grant; Image; Imaging Procedures; Imaging Techniques; Informal Social Control; Institution; Investigators; Macaca mulatta; Medical Imaging, Positron Emission Tomography; Monkeys; NIH; National Institutes of Health; National Institutes of Health (U.S.); Nervous; PET; PET Scan; PET imaging; PETSCAN; PETT; Positron Emission Tomography Scan; Positron-Emission Tomography; Proton Magnetic Resonance Spectroscopic Imaging; Rad.-PET; Research; Research Personnel; Research Resources; Researchers; Resources; Rhesus; Rhesus Macaque; Rhesus Monkey; Self Regulation; Social Behavior; Social Control, Informal; Source; Technics, Imaging; Thinking; Thinking, function; Training; United States National Institutes of Health; imaging; neural; relating to nervous system; skills; sociobehavior; sociobehavioral

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. This project is to modify our existing fear inhibition paradigm to permit its use longitudinally to investigate which specific orbital frontal sectors are involved in the acquisition and expression of conditioned inhibition in adult monkeys and second to follow longitudinally when orbital frontal regulation of conditioned inhibition emerged in primates of both sexes. We assembled the two new conditioning boxes and have modified these boxes to use multiple images as cues delivered via a computer screen instead of tone, light and fan as in our earlier studies. We have also programmed the delivery of the conditioned and unconditioned stimuli and have already acquired 9 female and 2 male monkeys. The paradigm was piloted on one monkey that learned successfully the task. Six new monkeys (2 males and 4 females) were started but only one of them was able to learn the task. We are now re-testing these animals using simpler visual stimuli (red square, yellow circle and blue star) instead of the more complex stimuli. Two have now learned the task and will progress on the test using different easy stimuli. Excessive fear and anxiety, along with an inability to overcome these emotions, are defining characteristics of many psychiatric disorders such as phobias, panic disorder, and posttraumatic stress disorder. Primate models of fear conditioning and fear inhibition provide useful tools to establish critical translational approaches to eventually develop novel treatments for disorders such as PTSD, where an inability to respond to safety signals is one of its core symptoms

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This project characterizes convergence of specific prefrontal cortex (PFC) inputs with the amygdala and temporal cortex in distinct striatal regions and investigates how this system undergoes refinement and reorganization consistent with postnatal milestones of behavioral development. We have currently ordered two rhesus monkeys (3-year-old and 1-year-old) to begin this project in January 2010 using MRI-guided injections of neuroanatomical tracers into the amygdala. We will (a) examine anatomical changes in cortex, striatum, amygdala and hippocampal pathways at the age of birth, 2-4 mo., 6 mo., 1 yr., and 3 years;(b) characterize the specific organization of cortical, amygdala, and hippocampal inputs to the striatum, with a particular focus on the refinement of diffuse projections and the convergence of focal projections;(c) will compare the models of convergent nodal regions across all age groups. Data obtained from such anatomical studies are clinically relevant because infancy through young adulthood is that critical time in which incentive-based learning forms the basis for behavioral guiding rules and the development of habits. Consistent with rapid behavioral development, the prefrontal cortex, amygdala, hippocampus and striatum undergo maturation during postnatal development. This time of developmental growth is associated with vulnerability to stress and the emergence of mental health problems including schizophrenia, depression, obsessive-compulsive disorders and addictions.

DESCRIPTION (provided by applicant): Memory impairments are common to many developmental disorders in humans, such as schizophrenia, autism, Williams syndrome, and anxiety, and are associated with dysfunction of the medial temporal lobe structures and prefrontal cortex. These disorders of unknown origin have significant impact on the normal cognitive development of a young individual, resulting in severe disabilities in the realms of perception, memory, language thinking, experience of emotions and social intelligence that span the entire life. The goal of our research program is to continue to follow the anatomical and functional development of the hippocampus and perirhinal cortex, and compare and contrast the long-term behavioral and neuroanatomical effects of early vs. late damage to this region. The overall hypothesis to be tested is whether early damage to the medial temporal lobe region yields the same behavioral changes, and anatomical and chemical re-organization than those seen after similar damage in adulthood. To achieve this we have characterized the normal development of macaque memory and compared it with that of monkeys with neonatal hippocampal (H) or perirhinal cortex (PRh) damage. We have completed the behavioral studies on normal and H lesioned infants up to 7 years of age, and of PRh lesioned infants up to 2.5 years old. The specific aims of the present application are 1) to continue our investigation of the role of the perirhinal cortex (PRh) in the development of memory processes and compare that with normal memory development as well as the impact of hippocampal (H) damage, as evaluated in the previous funding period, 2) to compare and contrast the effects of early PRh on behavioral responses and cognitive processes, such as emotional reactivity, social skills, and reward assessment, and compare that with controls and neonatal H lesioned animals from the previous funding period, 3) to characterize the impact of neonatal H damage on the maturation of the prefrontal cortex (PFC), using neuroimaging procedures to measure (a) metabolic activity of PFC with PET imaging and (b) structural, metabolites and white matter changes with T1W, MRS and DTI imaging. Post-mortem immunocytochemistry techniques will be used to quantify and correlate neuroanatomical and neurochemical changes in the PFC with those found with the neuroimaging techniques to validate the neuroimaging tools. These developmental studies will provide insights into the pathophysiology and etiology of devastating developmental human disorders and primate model of extreme value for the development of new therapies. PUBLIC HEALTH RELEVANCE: The effects of focal perinatal brain damage to the medial temporal lobe, though mild at first, can have serious and amplified consequences as the organism matures. Mild disturbances to one structure may grossly affect the development of another, potentially resulting in psychiatric disorders such as schizophrenia, autism, depression, posttraumatic stress disorder, and anxiety. However, our knowledge of the normal development, anatomically or behaviorally, is sparse at best in humans or non-human primates. Further, the behavioral and cognitive consequences of selective damage to this region are not well characterized. Finally, it is unknown whether brain plasticity mechanisms alleviate or worsen these effects by compromising the development of otherwise-undamaged brain regions. Understanding these consequences is key to early detection of the otherwise subtle effects of neonatal focal lesions, and of developing treatments in the future. The proposed studies provide a first step to that end and the results will broaden our understanding of developmental disorders and possibly lead to new therapeutic treatments.

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. This project examines the role of the primate amygdala in allocating visual attention to targets of emotional and social significance using reversible inactivation to separately manipulate two components of the amygdala complex;i.e. the centromedial and basolateral nuclear groups of the monkey amygdala. Since the funding of this project in September 2010, we have acquired a monkey and have instrumented this animal with a chamber that will allow access to the two nuclei. This animal has been also trained to fixate at a center point on a computer screen and visually explore images occurring at the fixation points. We have also acquired all the equipment to simultaneously record cell in the amygdala while injections of muscimol and bicuculine will either decrease or increase activity of the cells in the two amygdala nuclei. The results are expected to clarify the contribution of the amygdala to the acquisition of socially and emotionally relevant information-a critical prerequisite in designing a more effective intervention in socio-emotional disorders.

Autism is a disorder defined by altered engagement with the social world that emerges at early stages ofthe disorder. Thus, increase knowledge on the critical periods of typical development during which these early social skills emerge and mature and on the underlying neurobiological systems that underlie these skills will give unprecedented opportunity to further understand the neurobiological source of the early diagnosis markers of autism. Although research examining the precursors of human social abilities during early infancy has significantly increased in the last few years, critical information on the neural substrates that support these early developing social skills is still lacking. One ofthe main reasons being the limitations in neuroimaging the human brain in infancy, and to study brain-behavior relationship across development using longitudinal studies. Thus, knowledge in this domain must emerge from translational research examining both human populations and animal models. Rhesus monkeys provide a remarkable opportunity in this domain given (1) the rich and complex social structure in which they develop and navigate, (2) the progressive development of the basic social skills required to develop normal social relationships, and (3) the similarity with humans in brain and cognitive functions development. Thus, Aim 1 will follow longitudinally the development of social visual engagement processes, including attention to, detection and integration of social signals in normally developing rhesus monkeys from birth to 6 months, using neuropsychological marker tasks similar to those employed in the typical and atypical human population (Project I) to facilitate cross-species comparisons. This will allow defining significant critical periods during which these processes emerge and refine. Aim 2 will investigate in the same animals the maturational changes in brain networks mediating these basic social processes using noninvasive neuroimaging procedures. These studies on the normally developing rhesus monkeys will provide unparalleled information and a critical non-human primate model that could be used for further investigations targeting gene-behavior relationships and therapeutic interventions.

Abstract: The clinical spectrum of hippocampal (HIPPO) dysfunction encompasses a wide range of neurological, behavioral, cognitive symptoms in various psychopathological states, and importantly developmental neuropsychiatric disorders (Schizophrenia, Autism Spectrum Disorders, anxiety, post-traumatic disorders). Thus, the study of HIPPO and, in particular, of its interactions with dorsolateral prefrontal cortex (dlPFC) has become of major interest to further understand the neurobiology of developmental neuropsychiatric disorders in which both neural regions are affected and associated with memory impairment that are generally refractory to treatment. Although rodent and nonhuman primate models have proposed that HIPPO-dlPFC disconnection is an ideal systems-level phenotype that can be used for translation to neuropsychiatric diseases, these studies have been done in fully mature subjects limiting their translation to human disorders that emerge during development. A more meaningful approach would be to assess the critical developmental periods of HIPPO- dlPFC interactions and the consequences of their dysfunction across development. We propose to trace the development of HIPPO-dlPFC interactions in monkeys from pre-adolescence to adolescence, focusing on critical cognitive functions, i.e. episodic and working memory associated with HIPPO and dlPFC, respectively. At five age periods (pre-puberty: 18-30 mo, peri-puberty: 32-37 mo, 37-42 mo, 43-47 mo, and post-puberty: 52- 58 mo), we will measure HIPPO-dependent relational memory (object-in-place memory task) and PFC- dependent working memory (serial order memory task) in 15 male monkeys (Aim 1) in parallel to underlying developmental changes in HIPPO-dlPFC structural and functional connectivity (Aim 2), using noninvasive neuroimaging techniques (structural MRI, diffusion tensor imaging and resting state functional MRI). Aim 1 will provide the timing of strengthening of memory during peri-pubertal period and Aim 2 will indicate whether the memory changes are linked to changes in strength of PFC-HIPPO connections. In Aim 3, we will use six new pre-adolescent male monkeys for a transient HIPPO-dlPFC disconnection study. By combining HIPPO- inactivation in one hemisphere and dlPFC-inactivation in the other hemisphere, via muscimol (GABA-A agonist) injections, we will demonstrate that functional HIPPO-dlPFC interactions (Aim 2) are necessary for the emergence of adult-performance (Aim1). To control for pubertal effects on measures of the 3 aims, blood gonadal hormone and sexual morphological measures will be taken and used as predictors to assess the role of pubertal age on cognitive and neural changes. The proposed studies are novel, have high translational value, and will provide a new model system to carefully and systematically study the development of HIPPO- dlPFC interactions and the cognitive consequences of their derailment in adolescence and adulthood, avoiding confounding factors (pubertal age, cross-sectional studies etc) usually affecting data on human adolescents.

Abstract Neurodegenerative diseases that involve the basal ganglia commonly lead to cognitive impairments. In this proposal, we hypothesize that the massive projections from the thalamic parafascicular (PF) and centromedian (CM) nuclei to the caudate nucleus and the putamen, respectively, are key pathways that regulate cognitive processing, and that lesion of these thalamostriatal systems produce selective attention-related cognitive impairments in behavioral flexibility, habit learning, and possibly other forms of cognition. The CM and PF provide functionally organized glutamatergic projections that target striatal projection neurons and interneurons (particularly cholinergic interneurons). Functional imaging data from human and monkey studies have shown that CM and PF neurons respond strongly to behaviorally significant sensory events. It was also shown that CM/PF inputs to the striatum regulate responses of striatal tonically active neurons (TANs; likely corresponding to cholinergic interneurons) to salient reward-related stimuli, and that inactivation of Pf disrupts performance in attention tasks. Because the CM/PF complex profoundly degenerates early in the course of Parkinson?s disease (PD) and Huntington?s disease (HD), a detailed knowledge of the role of the CM- and PF-striatal projections will help us to understand the importance of the degeneration of these nuclei in the development of cognitive impairments in PD and HD. In this pilot project, we will evaluate the behavioral consequences of selectively lesioning the CM- or Pf-striatal projections in monkeys, using an immunotoxin lesioning approach. These preliminary studies will set the foundation for the development of a future R01 proposal that will assess the contribution of the primate thalamostriatal system to cognition. A better knowledge of the role of this projection system in normal basal ganglia function is essential to gauge the importance of its degeneration in neurodegenerative diseases.

PROJECT SUMMARY In humans, recent discoveries point to the importance of early-emerging and highly-conserved, quantitative mediating social phenotypes to advance understanding of the brain-behavior pathogenesis of Autism Spectrum Disorders (ASD). Thus, intact early, subcortically-guided, reflexive visual engagement performance is followed by a failed transition to cortically-guided, voluntary or reward-driven transition in early infancy. Our NHP brain- behavior studies suggest that 4-8 weeks of age (? 2-9 months for human infants) represents a critical period for the refinement of social skills, paralleled by fine-tuning of neural connections in social visual engagement pathways. Here, we propose a new generation of NHP studies that capitalizes on a remarkable convergence of findings yielded by current Emory ACE 2012 and related work and will include behavioral and neural measures similar to those used for human projects (P-I and P-III). 15 newborn male monkeys (Macaca mulatta) living with their mothers in large, socially complex, groups at the YNPRC Field Station will be used to: (a) characterize social visual engagement and neuromotor development (Aim 1); (b) trace development of early cycles of social contingency, adding a strong focus on mother-infant reciprocal behaviors given the apparent criticality of social contingency in moving social-communication development forward and identify early social predictors of later social competency (Aim 2); and (c) map the unfolding maturation of neural networks mediating changes in perception and attention to social stimuli, in mother-infant contingency cycles, and in the development of social competency, using longitudinal, non-invasive neuroimaging methods, and identifying early neural predictors of later social behavior outcomes (Aim 3). Data analyses will include new mathematical tools for optimal non- uniform sampling, developmental profiling, and inference of statistical causality to quantify the unfolding of social engagement between infant-mother, infant-peer, and infant-other adults (DMAC). This will allow us to (a) obtain developmental curves for each animal and detect potential outlier cases for follow up studies, (b) test temporal causality to address critical questions: Can early neurobehavioral measures in infancy predict social competency and detect abnormal social behaviors later in the juvenile period? Are the neurodevelopmental changes driving the behavioral changes, or vice-versa? The data will yield a critically needed NHP model of early social development for ASD that we will be used to (a) assess how genetic variations as well as molecular and/or experimental manipulations of social neural networks alter social development, and (b) validate efficacy of potential therapeutic treatments for attenuating social deficits in ASD.